Characteristics: Kava is a sprawling shrub of the black pepper family, it is cultivated widely throughout the South Pacific and no longer grows wild (Kuhn and Winston, 2000). The medicinal part is a four to six-year-old dried root.

History: The Polynesians from New Guinea to Tahiti have an ancient tradition of consuming the herb in ‘kava circles’ (Castleman, 2001). In the South Pacific, kava has been used traditionally as a treatment for headache, colds, arthritis, and as a sedative and aphrodisiac. Native people in Hawaii used to herb to control asthma. In the 18th century the British explorer, James Cook and his crew, were offered kava during their voyage exploring the islands of the South Pacific (1768-1771). The Eclectic physicians in 19th century America used kava for urinary tract pain, renal colic, chronic urethritis, neuralgia, mouth and throat pain, and dyspepsia (Kuhn and Winston, 2000). Kava is disussed in detail in the 19th century Eclectic text, ‘King’s American Dispensatory’, ‘(kava) appears to exert its influence more especially upon diseased mucous membranes… chronic inflammation of the neck of the bladder… in small doses, it is tonic and stimulant; while in large doses it produces an intoxication… It is of undoubted efficiency in acute vaginitis or urethritis, allaying the inflammation… It is a remedy for nocturnal incontinence of urine in the young and old… Prof. Webster… regards it as our most reliable remedy for neuralgia (Felter and Lloyd, 1898).

Around 1990, kava started becoming more widely used in the U.S.A. German studies had demonstrated low doses of kava produced no euphoria, but instead acted as a mild tranquilizer (Castleman, 2001; Kuhn and Winston, 2000). In the early 21st century reports of kava related liver toxicity emerged in the U.S.A., causing several European countries and the U.S.A. to ban the herb. Germany later repealed the ban in 2014 and so did the U.S.A. in 2012, but it remains illegal in other European countries like the U.K. It is possible that problems with the kava in the 1990s and early 2000s were related due to poor manufacturing standards where companies started selling the stem instead of the root which is toxic to the liver.

Current applications: Kava relives anxiety without effecting alertness (Kuhn and Winston, 2000). It is also used to treat tension headaches, muscle spasms, restless leg syndrome, back pain, and joint pain. It may be useful in cases of insomnia and menopausal anxiety. It may also be useful in pain control; urinary tract pain, muscle pain, and fibromyalgia. For fibromyalgia, it is applied alongside ashwagandha and black cohosh. It is sometimes applied to treat irritable bladder syndrome. Thomas Bartram recommends it in cases of gentio-urinary infections, urethritis, incontinence in old persons with bladder weakness, vaginitis, and chronic insomnia (Bartram, 2013). He also mentions it may be applied with black cohosh for rheumatism following STDs.

Science: There is substantial and convincing evidence that kava is effective against anxiety in humans (Kinzler et al., 1991; Boerner et al., 2003). There is additional evidence that it is effective against chronic insomnia. These studies confirm some of the traditional use of kava by herbal practitioners. There is evidence that kava can cause toxicity to the liver particularly with alcohol and other drugs, however, the side effect profile of kava remains better than pharmaceutical drugs for anxiety as discussed in a 2004 review article (Clouatre, 2004).

Safety: Moderate. Chronic heavy use of kava can lead to kawism where the skin becomes dry, flaky, and discoloured, although this effect reverses when discontinued (Kuhn and Winston, 2000). Some reports suggest that hepatotoxity or liver toxicity may be associated with poor manufacturing standards, with some companies using cheap stem peeling rather than the root.

Avoid chronic and heavy use, be extra cautious regarding dose if combining alcohol or sedatives with kava. Long term use of high doses and discontinuation likely will cause withdrawal effects. Do not use in individuals with a history of liver disease or with hepatotoxic drugs. Do not use in pregnant or breast-feeding women.

Dosage: Dried root; between 1.5g and 3g per day. Capsules; up to six 400mg capsules per day. Tincture; between 10-60 drops 2-3 times daily.

Scientific Summary

Research on humans

Anxiety: One study (n = 58, double blind placebo controlled) found that kava decreased anxiety significantly compared with the placebo (Kinzler et al., 1991). Dose was 3 x 100mg tablets per day of a special kava extract. No adverse effects were noted during the treatment.